1. Field of the Invention
The present invention relates to a zoom lens system having an image shake correcting capability, and to an image-sensing apparatus having an image shake correcting capability. More specifically, the invention relates to a compact zoom lens system having an image shake correcting capability for use in an optical unit or the like for capturing an image of a subject by use of an image sensor, in particular one having a zoom ratio (magnification variation ratio) of 7× or more, offering satisfactory optical performance from a wide-angle to a telephoto region, and suffering little degradation in performance when correcting image shake, and also relates to an image-sensing apparatus or the like incorporating such a zoom lens system.
2. Description of Related Art
Rapidly widespread in recent years, digital cameras are today widely used not simply as a means for capturing images into computers but also as a tool for creating photographs like conventional silver-halide cameras. With this trend, demands are increasing for compactness and for functions useful for creating photographs (for example, higher zoom ratios, wider angles of view, hand-shake correction, etc.). Moreover, with the ever-increasing number of pixels in image sensors, demands are also high for higher optical performance. Even in appliances (for example, camcorders) mainly for capturing moving pictures, demands are increasing for higher optical performance than ever to offer an enhanced still-picture shooting capability and to cope with high-definition TV.
As a means to meet these demands, U.S. Pat. No. 7,209,299 B2 proposes a vibration-damped zoom lens system composed of, from the object side thereof, a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, a fourth lens group having a negative optical power, and a fifth lens group having a positive optical power.
Disadvantageously, however, the zoom lens system disclosed in U.S. Pat. No. 7,209,299 B2 mentioned above is designed as an interchangeable lens for single-lens reflex cameras, and accordingly it has a zoom ratio as modest as about 5× and is not satisfactorily compact; it also suffers an unignorable degradation in performance when correcting image shake.